# std::filesystem::status, std::filesystem::symlink_status

From cppreference.com
< cpp‎ | filesystem

Defined in header `<filesystem>` |  |
std::filesystem::file_status status( const std::filesystem::path& p ); | (1) | (since C++17)
std::filesystem::file_status status( const std::filesystem::path& p, std::error_code& ec ) noexcept; | (2) | (since C++17)
std::filesystem::file_status symlink_status( const std::filesystem::path& p ); | (3) | (since C++17)
std::filesystem::file_status symlink_status( const std::filesystem::path& p, std::error_code& ec ) noexcept; | (4) | (since C++17)

1,2) Determines the type and attributes of the filesystem object identified by p as if by POSIX `stat` (symlinks are followed to their targets). In the following description, `prms` is the result of (m & perms::mask), where m is obtained as if by taking st_mode from the POSIX struct stat and converting it to the type std::filesystem::perms.

  - If p is a regular file (as if by POSIX S_ISREG), returns file_status(file_type::regular, prms).
  - If p is a directory (as if by POSIX S_ISDIR), returns file_status(file_type::directory, prms).
  - If p is a block special file (as if by POSIX S_ISBLK), returns file_status(file_type::block, prms).
  - If p is a character special file (as if by POSIX S_ISCHR), returns file_status(file_type::character, prms).
  - If p is a fifo or pipe file (as if by POSIX S_ISFIFO), returns file_status(file_type::fifo, prms).
  - If p is a socket (as if by POSIX S_ISSOCK), returns file_status(file_type::socket, prms).
  - If p has an implementation-defined file type, returns file_status(file_type::A, prms) where `A` is the implementation-defined `file_type` constant for that type.
  - If p does not exist, returns file_status(file_type::not_found).
  - If p exists but file attributes cannot be determined, e.g. due to lack of permissions, returns file_status(file_type::unknown).
  - If errors prevent even knowing whether p exists, the non-throwing overload sets ec and returns file_status(file_type::none), and the throwing overload throws `filesystem_error`.
  - Otherwise, returns file_status(file_type::unknown, prms).

3,4) Same as (1,2) except that the behavior is as if the POSIX `lstat` is used (symlinks are not followed):

  - If p is a symlink, returns file_status(file_type::symlink).

### Parameters

p | - | path to examine
ec | - | out-parameter for error reporting in the non-throwing overload

### Return value

The file status (a filesystem::file_status object).

### Exceptions

Any overload not marked `noexcept` may throw std::bad_alloc if memory allocation fails.

1,3) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument.
2,4) Sets a std::error_code& parameter to the OS API error code if an OS API call fails, and executes ec.`clear`() if no errors occur.

### Notes

The information provided by this function is usually also provided as a byproduct of directory iteration, and may be obtained by the member functions of filesystem::directory_entry. During directory iteration, calling `status` again is unnecessary.

### Example

Run this code

    #include <cstdio>
    #include <cstring>
    #include <filesystem>
    #include <fstream>
    #include <iostream>
    #include <sys/socket.h>
    #include <sys/stat.h>
    #include <sys/un.h>
    #include <unistd.h>

    namespace fs = std::filesystem;

    void demo_status(const fs::path& p, fs::file_status s)
    {
        std::cout << p;
        // alternative: switch(s.type()) { case fs::file_type::regular: ...}
        if (fs::is_regular_file(s))
            std::cout << " is a regular file\n";
        if (fs::is_directory(s))
            std::cout << " is a directory\n";
        if (fs::is_block_file(s))
            std::cout << " is a block device\n";
        if (fs::is_character_file(s))
            std::cout << " is a character device\n";
        if (fs::is_fifo(s))
            std::cout << " is a named IPC pipe\n";
        if (fs::is_socket(s))
            std::cout << " is a named IPC socket\n";
        if (fs::is_symlink(s))
            std::cout << " is a symlink\n";
        if (!fs::exists(s))
            std::cout << " does not exist\n";
    }

    int main()
    {
        // create files of different kinds
        fs::create_directory("sandbox");
        fs::create_directory("sandbox/dir");
        std::ofstream{"sandbox/file"}; // create regular file
        fs::create_symlink("file", "sandbox/symlink");

        mkfifo("sandbox/pipe", 0644);
        sockaddr_un addr;
        addr.sun_family = AF_UNIX;
        std::strcpy(addr.sun_path, "sandbox/sock");
        int fd = socket(PF_UNIX, SOCK_STREAM, 0);
        bind(fd, reinterpret_cast<sockaddr*>(&addr), sizeof addr);

        // demo different status accessors
        for (auto it{fs::directory_iterator("sandbox")}; it != fs::directory_iterator(); ++it)
            demo_status(*it, it->symlink_status()); // use cached status from directory entry
        demo_status("/dev/null", fs::status("/dev/null")); // direct calls to status
        demo_status("/dev/sda", fs::status("/dev/sda"));
        demo_status("sandbox/no", fs::status("/sandbox/no"));

        // cleanup (prefer std::unique_ptr-based custom deleters)
        close(fd);
        fs::remove_all("sandbox");
    }

Possible output:

    "sandbox/file" is a regular file
    "sandbox/dir" is a directory
    "sandbox/pipe" is a named IPC pipe
    "sandbox/sock" is a named IPC socket
    "sandbox/symlink" is a symlink
    "/dev/null" is a character device
    "/dev/sda" is a block device
    "sandbox/no" does not exist

### See also

file_status (C++17) | represents file type and permissions (class)
status_known (C++17) | checks whether file status is known (function)
is_block_file (C++17) | checks whether the given path refers to block device (function)
is_character_file (C++17) | checks whether the given path refers to a character device (function)
is_directory (C++17) | checks whether the given path refers to a directory (function)
is_fifo (C++17) | checks whether the given path refers to a named pipe (function)
is_other (C++17) | checks whether the argument refers to an other file (function)
is_regular_file (C++17) | checks whether the argument refers to a regular file (function)
is_socket (C++17) | checks whether the argument refers to a named IPC socket (function)
is_symlink (C++17) | checks whether the argument refers to a symbolic link (function)
exists (C++17) | checks whether path refers to existing file system object (function)
statussymlink_status | status of the file designated by this directory entry; status of the file/symlink designated by this directory entry (public member function of `std::filesystem::directory_entry`)

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/filesystem/status&oldid=180242"